Ingredients
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1 pound Zucchini
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1 pound yellow Summer Squash
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Kosher Salt
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Black Pepper
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1½ pounds ripe Tomatoes
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6 tablespoons extra-virgin Olive Oil
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2 Onion
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2 Garlic
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1 tablespoon minced fresh Thyme
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1 slice hearty white sandwich Bread
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2 ounces Parmesan Cheese
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2 Shallots
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¼ cup chopped fresh Basil
Directions
We loved the idea of a rich bread crumb–topped gratin showcasing our favorite summer vegetables: zucchini, summer squash, and ripe tomatoes. But every version we tried ended up a watery, soggy mess thanks to the liquid the vegetables released. To fix this problem, we salted the vegetables and let them drain before assembling the casserole. We baked the dish uncovered so that the remaining excess moisture would evaporate in the oven. Layering the tomatoes on top exposed them to more heat so that they ended up roasted and caramelized. To flavor the vegetables, we tossed them with an aromatic garlic-thyme oil and added a layer of caramelized onions. Fresh bread crumbs tossed with Parmesan and shallots made an elegant topping. The success of this recipe depends on high-quality vegetables. Buy zucchini and summer squash of roughly the same diameter. We like the combination, but you can also use just zucchini or summer squash. We prefer using kosher salt because residual grains can easily be wiped away from the vegetables; if using table salt, be sure to reduce all of the salt amounts in the recipe by half.
Steps
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1
Done
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Toss zucchini and summer squash with 2 teaspoons salt and let drain in colander until vegetables release at least 3 tablespoons liquid, about 45 minutes. Pat zucchini and summer squash dry firmly with paper towels, removing as much liquid as possible. |
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2
Done
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Meanwhile, spread tomatoes out over paper towel–lined baking sheet, sprinkle with 1 teaspoon salt, and let stand for 30 minutes. Thoroughly pat tomatoes dry with more paper towels. |
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3
Done
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Heat 1 tablespoon oil in 12-inch nonstick skillet over medium heat until shimmering. Add onions and 1 teaspoon salt and cook, stirring occasionally, until softened and dark golden brown, 20 to 25 minutes; set aside. |
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4
Done
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Combine 3 tablespoons oil, garlic, thyme, and ½ teaspoon pepper in bowl; set aside. Process bread in food processor until finely ground, about 10 seconds, then combine with 1 tablespoon oil, Parmesan, and shallots in separate bowl; set aside. |
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5
Done
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Adjust oven rack to upper-middle position and heat oven to 400 degrees. Grease 3-quart gratin dish (or 13 by 9-inch baking dish) with remaining 1 tablespoon oil. Toss zucchini and summer squash with half of garlic-oil mixture and arrange in greased baking dish. Sprinkle evenly with caramelized onions, then top with tomato slices, overlapping them slightly. Spoon remaining garlic-oil mixture evenly over tomatoes. |
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6
Done
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Bake until vegetables are tender and tomatoes are starting to brown on edges, 40 to 45 minutes. Remove gratin dish from oven and increase heat to 450 degrees. Sprinkle bread-crumb mixture evenly over top and continue to bake gratin until bubbling and cheese is lightly browned, 5 to 10 minutes. Let cool for 10 minutes, then sprinkle with basil and serve. |
